package com.demo.util;

import java.util.Map;

import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/** 
 *  
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候中取出ApplicaitonContext. 
 **/

public class SpringContextHolder implements ApplicationContextAware {

	private static ApplicationContext applicationContext;

	/** 
	 *  
	 * 实现ApplicationContextAware接口的context注入函数, 将其存入静态变量. 
	 */

	public void setApplicationContext(ApplicationContext applicationContext) {
		SpringContextHolder.applicationContext = applicationContext;
	}

	/** 
	 *  
	 * 取得存储在静态变量中的ApplicationContext. 
	 */
	public static ApplicationContext getApplicationContext() {
		checkApplicationContext();
		return applicationContext;
	}

	/** 
	 *  
	 * 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型. 
	 */

	@SuppressWarnings("unchecked")
	public static <T> T getBean(String name) {
		checkApplicationContext();
		return (T) applicationContext.getBean(name);
	}

	/** 
	 *  
	 * 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型. 
	 *  
	 * 如果有多个Bean符合Class, 取出第一个. 
	 */

	@SuppressWarnings({ "unchecked", "rawtypes" })
	public static <T> T getBean(Class<T> clazz) {
		checkApplicationContext();

		Map beanMaps = applicationContext.getBeansOfType(clazz);
		if (beanMaps != null && !beanMaps.isEmpty()) {//
			return (T) beanMaps.values().iterator().next();
		}
		return null;
	}

	private static void checkApplicationContext() {
		if (applicationContext == null) { //
			throw new IllegalStateException("applicaitonContext未注入,请在applicationContext.xml中定义SpringContextHolder");
		}
	}
}